This invention relates to machines for and methods of making cushioning dunnage product from stock material. The invention also relates to stock material for feeding the machine, as well as a method and a mechanism for producing this stock material. Lastly, the invention relates to a method of producing cushioning product via use of the stock material in the machine, and to product produced by the method.
Machines for making cushioning dunnage product have existed for a some time. U.S. Pat. No. 3,603,216 describes one such machine in which a multi-ply paper-like material is guided firstly in a converging chute which is a truncated pyramid in shape and which becomes thinner downstream so that the longitudinal edges of the material are rolled inwardly, and then secondly in a gear assembly between which the material travels. The central band of the resulting strip is grabbed by the teeth of two cooperating gears and pulled downstream as it is nipped by these gears. The two gears are mounted with spring means such that the gears are urged toward one another. The material is simultaneously compressed or coined, and the various layers are pressed together forming the coined strip. The product made by the machine comprises consequently a central coined strip and two pillow-like edges, and is suitable for padding shipping cases or boxes.
The main characteristic of this type of machine is that the same gears simultaneously pull the paper-like material downstream, and crumple and coin the multiply strip to connect the inwardly rolled edges to the central strip.
In practice, this plurality of functions can cause problems, these have been solved by various solutions, none of which is entirely satisfactory. Thus, when the pressure exerted on the sheets is sufficient to pull them downstream, the said sheets sometimes tear. On the other hand, if the pressure is reduced, the central strip is not held together firmly enough and sometimes the pillow-like edges come open or unroll, thus the material can consequently not be used as a cushioning dunnage product.
One of the proposed solutions to reconcile the two above requirements is described in U.S. Pat. No. 4,968,291 and is a gear-like stitching assembly having gear like members disposed in a meshed condition, characterized in that the teeth of at least one of the gear-like members have projections thereon for perforating the multi-ply formed material along the central coined section of the produced pad-like cushioning dunnage product.
However, the central coined area becomes more fragile, particularly where the projections of the teeth have made perforations, which are in fact beginnings of tears. The described machine can then only be used with superimposed sheets of high quality kraft paper, which is also much more expensive.
It is therefore one object of the present invention to provide a cushioning dunnage producing machine which does not suffer from the aforementioned disadvantages.
It will be appreciated then that machines producing dunnage product utilizing paper fed into the machine generally crumple the stock material running in a continuous strip, the crumpling being sometimes combined with other operations increasing the volume of the material. The final product must however be maintained in its final state, so that one can handle it without altering it. It must especially keep its resiliency and elasticity, imparted to it by the crumpling operation.
A double-layer band of paper leads to better results than a single-layer band of paper. This is because of the improved rigidity of the continuous strip. Also, the final dunnage product has greater volume due to the spaces appearing between the layers.
For maintaining the stability of the dunnage product, for improving the mechanical characteristics of the two layers and for making easier their passage in and through the dunnage producing machines, it is however preferable that the two layers be fixed to one another, for instance glued together. The easiest and least expensive way to glue them together would be by way of central axial linear gluing. However, due to the specific nature of the operations performed in combination with the crumpling operation to make the final dunnage product, it is preferable to increase the width of the glued area, or to glue the layers in two transversely distinct places. To get the maximum volume, it is moreover better not to glue the lateral edges of the two layers.
one solution could be to glue the two layers lengthwise in two parallel lines located in the central area, but such a technique would increase the production difficulties and hence production costs.
Another problem associated with the linear gluing is that it causes the formation of rolls increasing the thickness of the strip in the glued area, and it is then more difficult to roll or transversely fold the material, these operations being however needed for instance for stocking the material.
When the glue is applied continuously to the webs, i.e. linearly as described above, additional difficulties are encountered. The drying time is high, which decreases production speed, since to stock the material it must be wound around a roll, which winding action, if done prior to the glue having fully dried, can damage or deform the glued area of each layer. Further, such action can force the glue completely through the layers which is extremely undesirable as when the glue dries the layers of the roll all become adhered together.
Accordingly, another object of the invention is to provide a continuous material with at least two superimposed and glued layers, wherein the glued area does not form a roll which could prevent the material from being rolled or folded in good condition.
Yet another object of the invention is to provide for the production of the stock material while making significant glue savings on one hand, and allowing on the other hand the use of a large range of paper, not limited to high quality paper.
A further object of the invention is to provide for producing the material at a high production rate.
A still further object of the invention is to provide a solution which can easily be applied to the mechanisms making such multilayer materials, as well as a method of implementing this solution.
The present invention provides a machine of a very different design without the aforementioned drawbacks, with a combination of means for producing a an improved cushioning dunnage product with much higher cohesion. The product is made of recycled paper, which is much cheaper than higher quality paper, yet without the risk of tearing.
The machine performs the functions of pulling downstream the paper-like strip, crumpling and connecting it, in order to make a high cohesion product, the functions being provided by separated parts, each one being adapted to the function to be performed, and thus ensuring total efficiency of the machine.
The components providing for the pulling downstream are two superimposed wheels. One wheel of the pair of wheels is a cylindrical shaped wheel, called a pulling wheel. The median portion of this pulling wheel includes an annular groove, while the edge portions are milled or knurled, these edges including flat parts along their periphery, located so that the flat parts of one edge portion face the non flattened parts of the other edge portion. The other wheel, called a support wheel, also has an approximately cylindrical shape, and includes a median portion with a toric strip corresponding to the annular groove of the upper wheel, and two cylindrical edge portions in contact with the non flattened areas of the upper wheel.
The superimposed sheets of the multi-ply formed material are nipped and driven between the cylindrical portions of the pulling wheel and the non flattened parts of both the edge portions of the support wheel, i.e. alternately the right and the left edge portions. The sheets are consequently not pulled downstream axially, but alternately by the left portion and by the right portion, with respect to the central axis, the resulting lateral dissymetry being balanced by the median hollow flexible area created between the toric strip and the annular groove. Due to this driving mode, the efforts exerted on the sheets do not result in tearings thereon, because of the lack of stresses, except the stress for the axial pulling downstream.
The components performing the connection of the superimposed sheets are a second set of two wheels, downstream from the first set of two wheels. One wheel of the second set is castellated and the other wheel of the second set is smooth, the periphery of the teeth of the one wheel rotating on the smooth surface of the other wheel, and the superimposed sheets being then compressed by the teeth acting against the smooth surface. There are no risks of tearing, because the sheets are not deformed between gear like members meshing together.
The components performing the crumpling operation comprise a reducing gear assembly linking the pulling wheels and the connecting wheels so that the pulling wheels rotate 1.9 times the rate of the connecting wheels. Due to the difference of speeds, the material is fed into the connecting wheels faster than the rotation of connecting wheels, the result being that the paper is compressed and crumpled without stresses.
There is consequently a combination of means and results, acting from rearward to forward, between the driving wheels, the reducing gear assembly and the connecting wheels, in order to make the final product, i.e. a pad-like product having a high cohesion, without risking any tearings.
This new design, contrary to the usual designs for this kind of machine, allows the use of paper of inferior quality, less expensive than kraft paper, for instance recycled paper of poor quality, which would not be possible in the typical machines mentioned above.
The present invention relates also to several improvements for the system described above.
Due to the fact that the driving is performed only by the rear wheels, while the connecting wheels do not exert a big pressure, it is possible to mount the axes of the support wheel and the smooth wheel on rocking levers upon which act springs positioned so that the actions of the springs are stronger rearward, i.e. for the driving function, than forward, i.e. for the connecting function. In practice, the two sets of wheels are mounted in a cradle with the axes of the pulling and castellated wheels being fixed within the cradle and reducing gear assembly linking them, whereas the support and the smooth wheel axes are placed along a rocking lever rotating backwards and forwards, and coacting with a set of two springs exerting pressure on a point of the rocking lever located between the rear end and the front end, at about a distance of {fraction (1/3 )} from the rear end.
The invention relates also to a simplified system providing for feeding the paper in the machine, ensuring an optimization of the quantity of material being fed into the whole mechanical system, which will be described hereinafter.
The present invention relates also to a method for making cushioning dunnage product from a multi-ply formed paper-like material, after having folded back the lateral edges on the central portion, by pulling downstream the material, crumpling it transversely, and compressing it along successive areas to maintain it. The main characteristic of the method is that all of the previous steps are made successively and separately. Preferably, the crumpling is the consequence of the braking of the material downstream of the driving stage, without any additional means acting directly on the material.
The invention further relates to a new cushioning dunnage product resulting from the above method, having a sufficient dunnage because of the crumpling and an excellent cohesion because of the connecting and of the compression, but being without weak areas; it is therefore possible to make it out of recycled paper, in particular.
According to another aspect of the invention, stock material for feeding into the above-described machine is provided wherein the layers of the material are glued in a variable width axial area by a gluing material applied according to a periodic curve, in the plan of the axial area, between the layers, the width of the area being adjustable by controlling the amplitude of the curve.
The curve is preferably sinusoidal like, preferably located centrally in relation with the transverse dimension of the layers.
One of the most interesting advantages of the material according to the invention is that all types of paper can be employed, and more particularly all different grammages. Thus, at least one of the layers or web may consist of Kraft paper.
When one of the two webs are made of Kraft paper, the latter can be chosen between all of the market available qualities.
As far as the glue saving is concerned, the glue is preferably applied discontinuously. This prevents moreover the glued area from getting too wet, and the attendant disadvantages described above.
The glue utilized in the present invention is preferably an emulsion of plastified homopolymeric polyvinyl acetate which dries quickly. This glue is also characterized by a high molecular weight and an average viscosity appropriate for papers.
The chosen papers can even be biodegradable and recyclable. Due to the aforementioned particularities, the chosen glue does not damage or weaken the papers, although they are generally considered as less solid, especially when they are moistened.
The multiply continuous paper-like band finally produced can then take several shapes for feeding a machine producing cushioning dunnage. It can be for instance wound around an axis to form a roll which is then continuously unwound to be folded and crumpled in the machine.
The invention relates also to a method for making such a band comprising the following steps:
unwinding the webs forming the layers parallel and at the same speed, the non identical central axes of the webs when unwound being in a plane perpendicular to the planes of the webs themselves;
gluing the facing sides of the webs, according to a periodic curve having an amplitude defining a gluing axial area;
bringing into contact the facing surfaces of the webs so that the central axes are merged.
The invention further relates to a mechanism for making the multilayer material of the invention, wherein the periodic curve drawn by the gluing material is performed on at least one layer by means of a buckled wheel having its periphery in contact on one hand with a system applying glue on the periphery and on the other hand with the layer, the buckled wheel being moved when the layers are being unwound, both speeds being then synchronized.
In order to save glue and also to prevent the low quality papers from being overly moistened, the buckled wheel is castellated. Thus, the periodic curve of the applied glue is discontinuous.
In the dunnage product made by the machine of the invention, the lateral edges of the stock material are folded inwardly, then crumpled, and the edges are finally connected in the central area of the band. This connecting operation is performed along an axial area having a predetermined width, corresponding approximately to the gluing area, and improves the quality of the crumpling of the dunnage product finally obtained.
According to yet another aspect of the invention, a method of making cushioning dunnage with the paper of the invention in the machine of the invention is provided. An elongated band of stock material is provided. The stock material has lateral edges and a longitudinal axis, and is formed from at least two elongated paper webs adhered together along the lengths of the webs by glue applied to one of the webs in a gluing area having a length along a longitudinal axis of the one web and a width transverse to the one web longitudinal axis, the transverse location of glue applied to the gluing area varying as a function of the longitudinal location along the gluing area. The band is driven longitudinally. The lateral edges of the band are folded laterally inwardly. The band is alternatingly crumpled longitudinally on first one side of the longitudinal axis of the band and then on the other side of the longitudinal axis of the band to form pleats in the band. The pleats in the band are connected by compressing the band through the thickness of the band.
The glue is preferably applied to the one web according to a periodic curve. The periodic curve is preferably sinusoidal. The glue is preferably applied to the one paper web centrally of the transverse dimension of the web. One of the paper webs may be Kraft paper. One of the paper webs may be made of biodegradable and recyclable paper. The glue may be applied discontinuously along the length of the periodic curve of application. The glue is preferably an emulsion of plastified homopolymeric polyvinyl acetate. The elongated band of stock material may be provided wound in a roll which is unwound as the band is driven longitudinally. The driving step and the connecting step of the method are preferably separate steps performed successively and independently of one another. The driving step is performed at a driving stage, the crumpling step is performed at a crumpling stage and the connecting step is performed at a connecting stage, and the crumpling step at the crumpling stage preferably occurs by virtue of the longitudinal speed of the band at the driving stage being greater than the longitudinal speed of the band at the connecting stage. The connecting step is preferably performed approximately across the width of the gluing area.
The invention also provides cushioning dunnage made according to the above methods.